The present invention relates generally to an ECM (Electronic Countermeasures) preprocessor or tracker of signal emissions, including radar, using multi-processor modules.
Prior power management systems for electronic warfare signal processing have a relatively slow information processing pipeline in which data is sensed, then evaluated, a reaction chosen, the chosen reaction formulated and finally the environment stimulated by ECM transmission. Essentially the pipe is a U-shaped structure as shown in FIG. 1. To accommodate required system functions, bridges between input and output chains to provide functions such as predictive tracking are included so that information is used to control the output more quickly and directly than is possible by taking the long path around the loop.
A tracking system has the job of predicting in real time the parametric behavior of radar signals to be jammed, future threat events (radar pulses, sonar pulses, etc.) By knowing when a pulse will arrive before it actually does, data from the pulse echo can be obscured (jammed) so as to reduce either the threat of detection or the accuracy of the resulting detection information. The term "tracking" has to do with occasionally taking a look at the signal so prediction errors can be corrected. The result is that the prediction adjusts its signal model as the signal changes. Hence the predictions "track" the signal.
Parameters to be predicted include the time of arrival (TOA), the radio frequency (RF), the amplitude. and the angle of arrival (AOA) of each pulse from a radar emitter. The time of arrival depends upon the pulse repetition interval (PRI), which is also referred to by the pulse repetition frequency (PRF). A stable signal is one for which the pulse repetition interval and other parameters are the same from pulse to pulse. A stagger signal is one for which the pulse repetition interval changes either from pulse to pulse or with some other cyclically repeating pattern. An agile signal is one for which other parameters such as frequency or amplitude change with a cyclically repeating pattern.
Very high speed integrated circuit (VHSIC) technology should make it possible to improve many characteristcs of signal processing systems. It would be highly desirable to develop a programmable interconnection scheme which permits processes to communicate without rigid restrictions. The prior art system structure required special trackers, special purpose presorters, special purpose waveform generators, video processors and the like.
An object of the invention is to provide a unit which can be integrated into a fully programmable system as opposed to a rigid system with varying degrees of programmability at the module level. A further object is to provide a programmable preprocessor which would allow a common hardware design to be used for a wide variety of preprocessing functions. The advantages include an increase in flexibility and a substantial reduction in overall life cycle cost for the system due to the use of a standardized hardware design.
The back end general purpose processing has been the subject of extensive work aimed at standardization and miniaturization. More recently, the middle ground of programmable vector signal processors has been subjected to similar efforts to reduce size and introduce programming standards. Certainly, the idea of building signal processors which are functionally modular, which are built from a small set of elemental module types and which are made to perform completely different tasks by programming is not new for either computers or signal processors. However, at the front end of a power management system, a sizable portion of the digital processing hardware is contained and little or no prior work has been done to apply the same principles used in the back end processing.
An object is to categorize the front end tasks by precision, dynamic range, memory capacity and speed requirements and then design a common processing module to solve all problems which have similar requirements.
It is clear that tracking and waveform generation have great similarity. They are both essentially signal models. With feedback, they are called trackers. Without it, they are just open loop signal generators. In prior systems, the two functions are usually performed by different special purpose processors.
U.S. patents of interest include U.S. Pat. No. 4,217,580 to Lowenschuss, which discloses an electronic contermeasure system for automatically identifying radio frequency energy sources and assigning countermeasures to such sources when required. The electronic countermeasure system includes signal processing apparatus which enables only a predetermined number of digital words associated with one of a plurality of radio frequency energy sources to pass to a general purpose digital computer. U.S. Pat. No. 4,025,920 to Reitboeck et al discloses a radar system which includes signal processing equipment for identifying radar signals from selected ones of their parameters such as azimuth, frequency, pulse duration and the like. U.S. Pat. Nos. 4,209,835 to Guadagnolo; 3,943,5I5 to Miley; and 3,764,999 to Simons et al disclose electronic countermeasure systems which use computer processing apparatus and are of general interest.